Prevalence of CO2 from disused mineral mines and the implications for residential buildings: research

1 Executive Summary

During April 2014, a number of cases of ill health were reported to be affecting some residents in the former mining area of Gorebridge, Midlothian. An Incident Management Team (IMT) was set up by NHS Lothian and a report compiled which produced wide ranging recommendations, some of which related to the Building Standards Division within Scottish Government.

RSKW were commissioned, in September 2018, to undertake fact finding research to investigate the prevalence of CO2 from disused mineral mines and implications for residential buildings.

The aims of the research project were the following:

• Identify organisations who have produced guidance on mine gas mitigation;
• Build-up an inventory of similar events in Scotland; and
• Explore the building standards related issues in the Gorebridge IMT report.

The issues explored, as part of a process of stakeholder engagement and consultation with experts, included eight building standards related recommendations in the Gorebridge IMT report:

• The risk assessment process
• Mitigation measures
• Construction techniques
• Energy efficiency measures/airtightness
• Consideration of mandatory mine gas mitigation in selected areas
• Retrofitting of mitigation measures to existing properties

The project requirements were set out by the Building Standards Division and in responding to the project aims above, we have provided several options for consideration to reduce risks from CO2 mine gas. Following our investigation, consultation and analysis, the proposed options for further consideration are as follows:

1. Use and enforcement of model planning conditions and/or changes to Scottish Planning and Building Standards and guidance to ensure adequate risk assessment of mine gas and design, construction and verification of gas protection measures.

2. Further research and preparation of supplementary technical guidance relating to the assessment of risks to new and existing developments from mine gas.

3. Consideration of mine gas issues and constraints at local development planning stage, especially related to large-scale developments and cumulative effects.

4. Improved co-ordination and communication between Planning, Building Standards and the Environmental Health/Contaminated Land staff in some local authorities.

5. Further research to assess the long-term effectiveness of granular fill and perforated pipe ventilation below slab construction.

6. Further consideration of the implementation of mandatory mitigation measures in former coal/oil shale mining areas.

7. Additional liaison between Scottish Government, Scottish Local Authorities and Northumberland County Council may be mutually beneficial.

8. Validation of risk assessment and mitigation design experience of consultants within the developers’ procurement process.